This invention concerns antihistamines in general, and more particularly, those which block the H.sub.2 -receptors.
It is known that histamine, a physiological compound which is found in living organisms, may be bound to certain specific receptors for exerting its activity. Two types of histamine receptors have been identified so far: H.sub.1 -receptors, in which the action of histamine is blocked by conventional antihistamine drugs, for example, mepyramine (Ash and Schild: Bri. J. Pharmac, Chemother., 27, 427-39, 1966); and H.sub.2 -receptors, in which the action of histamine is blocked by cimetidine (Black et al: Nature, 23(6), 385-90, 1972). The blockade of histamine activity by H.sub.2 -receptors results in the inhibition of gastric acid secretion, thus making the compounds with this potency effective for the treatment of peptic ulcers and other pathologies caused or stimulated by gastric acidity.
However, the known compounds are not always satisfactory and there is always a need for improved pharmaceuticals of this nature.